I'd like to point out, that while your little HEX module is handing it's easily replaceable.
For dealing with hex values
&H
that reverse hex is just declaring the proper variable
dim byte1 as byte'Handles 1 byte
byte1=&H0C
viewing with a hex editor you'll see 0x
dim integer1 as integer'Handles 2 bytes
integer1=&HFF04
viewing with a hexeditor
04 FF

and the one I guess that reversehex is mainly used for

the long

dim long1 as long'4 bytes usually for a pointer
long1=&h8123456
in a hex editor
56 34 12 08
Get it now?

Readhex is simply reduced to
dim byte1 as byte
open filepath for binary as #1
get #1, offset+1,byte1
or
seek #1, offset+1
get #1, ,byte1
close #1
for integers

just change the byte to integer

for long just change integer or byte to long

to write data to a rom use put instead of get

and to extract the address from a long
just take the 8 off so
offset-&h8000000

make sure if you're pointing a pointer into a rom make sure to add the &H8000000